Iupac Nomenclature MCQ Quiz in मल्याळम - Objective Question with Answer for Iupac Nomenclature - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

Concept:

The IUPAC (International Union of Pure and Applied Chemistry) system of nomenclature provides standardized rules for naming organic compounds to ensure consistency and clarity. The following rules are typically followed for naming compounds:

Rules for IUPAC Nomenclature:

• Step 1: Identify the Parent Chain: The parent chain is the longest continuous chain of carbon atoms that includes the principal functional group. In this case, the benzene ring is the parent structure.

• Step 2: Identify and Prioritize the Functional Groups: The functional groups attached to the parent chain are given positions based on the lowest possible locants (numbers). Functional groups are prioritized based on the IUPAC priority rules.

• Step 3: Assign Locants and Name the Substituents: After assigning positions (locants) to the functional groups, the substituents are named in alphabetical order, followed by the parent chain.

• Step 4: Write the Full Name: Combine the locants, substituents, and parent name to create the IUPAC name.

Priority of Functional Groups (Decreasing Order):

1. Carboxylic acids (-COOH)
2. Nitriles (-CN)
3. Aldehydes (-CHO)
4. Ketones (-C=O)
5. Alcohols (-OH)
6. Amines (-NH₂)
7. Halogens (e.g., -Br, -Cl, -I)

Explanation: 

In the given compound, the parent structure is a benzene ring, and the functional groups attached are a hydroxyl group (-OH), a bromine atom (-Br), and a nitrile group (-CN). According to IUPAC rules, the nitrile group (-CN) has the highest priority and is given position 1. The hydroxyl group (-OH) is positioned at 5, and the bromine atom (-Br) is positioned at 2. Therefore, the correct IUPAC name is **2-Bromo-5-hydroxybenzonitrile**.

Conclusion:

The correct answer is option 2: "2-Bromo-5-hydroxybenzonitrile."

Explanation: 

• 

• The nitrile group (-CN) is given position 1 as it is the principal functional group in the compound.

• The bromo group is placed at position 2, as it follows the priority order and ensures the lowest locants for the substituents.

• The hydroxyl group (-OH) is placed at position 5, completing the numbering of the compound.

Conclusion:

The correct IUPAC name of the compound is: 2-Bromo-5-hydroxybenzonitrile

Concept:

The IUPAC nomenclature of bicyclic compounds, particularly bridged bicyclic systems, follows specific rules to ensure clarity in identifying the structure. The nomenclature involves indicating the two rings, the bridge lengths, and the total carbon atoms in the system.

Rules for Naming Bridged Bicyclic Compounds:

• Step 1: Identify the Number of Rings: A bicyclic compound contains two fused or bridged rings. The two rings share atoms, including those in the bridge.

• Step 2: Count the Total Number of Carbons: Identify the total number of carbon atoms in the compound. This number gives the base name, like octane (8 carbons) or heptane (7 carbons).

• Step 3: Identify the Bridges: The compound may have one or more bridges connecting the rings. The number of carbon atoms in each bridge is counted, excluding the shared atoms.

• Step 4: Write the Bicyclo Descriptor: The compound is named as "bicyclo[x.y.z]" where x, y, and z represent the number of carbon atoms in each of the three bridge sections, listed in decreasing order.

• Step 5: Include Double Bonds or Functional Groups: If the compound has a double bond or other functional group, this should be indicated by the position of the bond and the suffix (e.g., -ene for an alkene).

Explanation: 

• The structure of 2-methylbicyclo[2.2.1]hept-2-ene consists of a seven-membered bicyclic system. The double bond is located at carbon 2, which is indicated by the suffix "-2-ene." and methyl group is present at carbon 2 as well.

• The correct structure should have two 2-carbon bridges and one 1-carbon bridge, which is characteristic of the [2.2.1] system. The structure must also have a double bond at the second carbon position.

• 

Conclusion:

The correct structure for 2-methylBicyclo[2.2.1]hept-2-ene is represented by Option 3.

Concept:

The IUPAC nomenclature of bicyclic compounds, particularly bridged bicyclic systems, follows specific rules to ensure clarity in identifying the structure. The nomenclature involves indicating the two rings, the bridge lengths, and the total carbon atoms in the system.

Rules for Naming Bridged Bicyclic Compounds:

• Step 1: Identify the Number of Rings: A bicyclic compound contains two fused or bridged rings. The two rings share atoms, including those in the bridge.

• Step 2: Count the Total Number of Carbons: Identify the total number of carbon atoms in the compound. This number gives the base name, like octane (8 carbons) or heptane (7 carbons).

• Step 3: Identify the Bridges: The compound may have one or more bridges connecting the rings. The number of carbon atoms in each bridge is counted, excluding the shared atoms.

• Step 4: Write the Bicyclo Descriptor: The compound is named as "bicyclo[x.y.z]" where x, y, and z represent the number of carbon atoms in each of the three bridge sections, listed in decreasing order.

• Step 5: Include Double Bonds or Functional Groups: If the compound has a double bond or other functional group, this should be indicated by the position of the bond and the suffix (e.g., -ene for an alkene).

Explanation: 

• Using the IUPAC rules for bicyclic compounds, the structure shown has a total of 8 carbon atoms, so the base name is octane.

• 

• The compound has three bridges, and each bridge contains 2 carbon atoms, making it a bicyclo[2.2.2] structure.

• There is a double bond present at the second carbon, which gives it the suffix "-ene." The position of the double bond is numbered as 2, making the correct suffix octa-2-ene.

• Thus, following the rules, the IUPAC name of the compound is Bicyclo[2.2.2]octa-2-ene.

Conclusion:

The correct IUPAC name of the compound is Bicyclo[2.2.2]octa-2-ene.

The correct answer is 4–Methyl–4–hexen–2–yne

Explanation:-

- The compound in question has both a double bond (ene) and a triple bond (yne) in its structure. In IUPAC naming, the chain is numbered in a way that gives the multiple bonds the lowest possible numbers.
- The correct name is 4-Methyl-4-hexen-2-yne, which indicates a six-carbon chain (hex) with a double bond starting from the fourth carbon (4-hexen) and a triple bond starting from the second carbon (2-yne), along with a methyl group attached to the fourth carbon (4-Methyl).
- This name correctly reflects the positions of the functional groups and the substituent according to IUPAC rules, ensuring the lowest possible numbers for the multiple bonds while also numbering from the end of the chain that gives the substituent the lowest number.

Conclusion:-

So, The correct IUPAC name of the following compound is 4–Methyl–4–hexen–2–yne

The correct answer is pyrano[2',3':4,5]cyclohepta[ 1,2-g]quinoline

Concept:-

A system where each bond is part of a ring; where each ring is ortho-fused (FR-l.l.l), or ortho- and perfused to at least one other ring; and where no bond is common to more than two rings is termed a fused ring system.

• Bridged fused ring system 
• A ring system where some of the rings constitute a fused ring system and the remaining rings are created by one or more bridges (FR-1.4) is termed a bridged fused ring system.
• Multiparent name
• A (used ring system name which is constructed using an interparent component (FR-1.3.3) and two or more identical parent components (FR-1.3.1) is called a multiparent name.
• Multiplicative prefix name
• A fused ring system name which is constructed using one or more multiplicative prefix(es) (di-, tii-, etc. or his-, tris-, etc.) to indicate multiple occurrences of the attached component(s) (FR-1.3.2) is called a

multiplicative prefix name. 

Explanation:-

Components of a fused ring system

• Allowed fusion components are rings or ring systems which can be named without the application of any fusion nomenclature principles (see Appendices 1 and 2). Fused ring systems which do not have such a name are named by joining together appropriately selected fusion components. 

Parent component

• The parent component (referred to as the base or principle component in previous versions of these rules) is the one with highest seniority according to the criteria given in FR-2.3 and is represented in the fusion name by that ring or ring system which is cited last in the name. It may be mono- or poly-cyclic (see FR-1.3.2 for an example).

Attuched component(s)

• The components of a fused ring system which are not covered by the parent component are called attached component(s) and are expressed by fusion prefixes. Prefixes denoting components directly fused to the parent component are called first-order fusion prefixes. The rest are called second-order, third-order, etc. fusion prefixes which means they correspond to the second, third, etc. component reached when moving away from the parent component across fusion sites. All attached components may be mono- or poly-cyclic. 

Parent component - quinoline
First-order fusion prefix - cycloheptal
Second-order fusion prefix - pyrano

IUPAC name is pyrano [2',3':4,5] cyclohepta [ 1,2-g ] quinoline

Conclusion:-

So, the IUPAC name is pyrano [2',3':4,5] cyclohepta [ 1,2-g ] quinoline.

Concept:

IUPAC Nomenclature:

• The IUPAC nomenclature of organic compounds is a method for naming organic chemical compounds.
• Alkanes with unbranched carbon chains are simply named by the number of carbons in the chain. The first four members of the series (in terms of the number of carbon atoms) are named as follows: 
  • ​CH4 = methane = one hydrogen-saturated carbon, 
  • C2H6 = ethane = two hydrogen-saturated carbons, 
  • C3H8 = propane = three hydrogen-saturated carbons, 
  • C4H10 = butane = four hydrogen-saturated carbons.
• Alkanes with five or more carbon atoms are named by adding the suffix -ane to the exact numerical multiplier, except the terminal -a, is removed from the basic numerical term. Hence, C5H12 is called pentane, C6H14 is called hexane, and C7H16 is called heptane.
• According to the IUPAC rule, the longest continuous chain of carbon atoms is the parent chain. 
• In the case of alkene, the suffix -ane of an alkane is replaced by -ene.
• Priority of groups is based on the atomic mass of attached atoms not on the size of the atom.

​IUPAC Rules of R/S or CIP Nomenclature:

• The C atom with four different groups is called the chiral center and the groups attached to the chiral carbon is assigned based on priority order.
• The priority of groups or atoms increases with an increase in atomic number and vice versa.
• If the same atoms are attached directly to the chiral center, then the β-atoms are taken into consideration to determine the priority sequence.
• If the β-atoms also fails to determine the priority of the atoms, γ-atoms are chosen. In some cases, γ- and further groups are considered until a decision regarding the priority sequence is arrived.
• Then draw an arrow starting from a low priority group to the highest priority group in order from priority 1 and going to priority 2 and then to priority 3.
• If the arrow goes clockwise then the configuration is R when the lowest priority group is placed away from the viewer, whereas the configuration will be S when the lowest priority group is placed towards the viewer.

Explanation:-

• The longest chain has seven carbon atoms.
• So the parent name of the compound is hepta.
• The only functional group present in the compound is alcohol.
• The main priority of the functional group is alcohol.
• According to IUPAC nomenclature, the suffix name of the alcohol is -ol.

• Now, the priority order of the different groups are as follows:

• The confirmation at C-3 is S as the arrow goes anti-clockwise and the lowest priority group is placed away from the viewer.
• The confirmation at C-4 is R as the arrow goes anti-clockwise but the lowest priority group is placed towards the viewer.

Conclusion:-

• Hence, the configuration at the two chiral centers in the compound given below are 3S, 4R.

Correct answer: 3)

Concept:

• Rules for assigning an R/S designation to a chiral center
• Assign priorities to the four substituents,1 being the highest priority and 4 the lowest.
• Priorities are based on the atomic number.
• Trace a circle from 1 to 2 to 3.
• Determine the orientation of the lowest priority group (4).
• If it is oriented into the plane of the page (away from you), go to step a. If it is oriented out of the plane of the page (toward you) go to step b.
• a: (lowest priority groups pointing away from you): a clockwise circle corresponds to the R configuration, while a counterclockwise circle corresponds to the S configuration.
• b: (lowest priority group pointing toward you): a clockwise circle corresponds to the S configuration, while a counterclockwise circle corresponds to the R configuration.

Explanation:

• Give each atom connected to the chiral center a priority based on its atomic number.
• The higher the atomic number, the higher the priority.
• So, based on this, the oxygen atom of the alcohol functions group (-OH) gets the highest priority (1), and the carbon of the COOH group gets priority two.

• 2R-3S is the configuration of the given compound.

Conclusion:

Thus, the correct configuration is 2R and 3S.

Key Points

• Ethanoic acid is the systematic IUPAC name for acetic acid.
• Acetic acid is a simple carboxylic acid with the chemical formula CH₃COOH.
• The IUPAC naming system is used to provide a standard way to name chemical substances, ensuring that each name is unique and universally understood.
• The prefix "eth-" indicates that the molecule contains two carbon atoms.
• The suffix "-oic acid" signifies that the compound is a carboxylic acid.

Additional Information

• Acetic acid is widely used in the food industry as a preservative and flavoring agent, commonly known as vinegar.
• The compound is also used in the production of chemical compounds such as acetate esters and acetic anhydride.
• In the industrial sector, acetic acid is used in the manufacture of plastics, textiles, and as a solvent.

Correct answer: 2)

Concept:

• In IUPAC nomenclature, the base part of the name reflects the number of carbons in what you have assigned to be the parent chain.
• The suffix of the name reflects the types of functional groups present on (or within) the parent chain.
• Other groups which are attached to the parent chain are called substituents.
• Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic.

Explanation:

• The structure of Glycerol:

• Here, the –OH groups are the functional groups.
• The number of carbon atoms in the above structure is 3 and all the bonds between the Carbon atoms are single bonds.
• So, the IUPAC name starts with Propane.
• Three –OH groups are attached to the Carbon atoms at positions 1, 2, and 3.
• Therefore, the IUPAC name of glycerol is Propane-1,2,3-triol.

Conclusion:

Thus, the IUPAC name of glycerol is 1, 2, 3 - propane triol.